Methods for selective integration of airgaps and devices made by such methods

Abstract

Methods for the production of airgaps in semiconductor devices and devices produced using such methods are disclosed. An example semiconductor device includes a damascene stack formed using such methods. The damascene stack includes a patterned dielectric layer including an interconnect structure, where the dielectric layer is formed of a dielectric material including Si, C and O. The damascene stack also includes a converted portion of the dielectric layer, where the converted portion is adjacent to the at least one interconnect structure and has a lower carbon content than the dielectric material. The damascene stack also includes an airgap formed adjacent to the interconnect structure, the airgap being formed by removing at least part of the converted portion using an etch compound.

1. A damascene stack for use in a semiconductor device, the damascene stack comprising:
 a patterned dielectric layer including an interconnect structure, wherein the dielectric layer is formed of a dielectric material including Si, C and O; 
 a converted portion of the dielectric layer, wherein the converted portion is adjacent to the interconnect structure and has a lower carbon content than the dielectric material; and 
 an airgap formed adjacent to the interconnect structure, the airgap being formed by removing at least part of the converted portion using an etch compound. 
 
   
   
     2. The damascene stack of  claim 1 , wherein the etch compound includes fluorine. 
   
   
     3. The damascene stack of  claim 1 , wherein the converted portion of the dielectric layer is formed by local converting the dielectric material during patterning of the interconnect structure. 
   
   
     4. The damascene stack of  claim 3 , wherein the interconnect structure is patterned using a dry etch sequence. 
   
   
     5. The damascene stack of  claim 4 , wherein the interconnect structure is patterned using an oxidizing plasma. 
   
   
     6. The damascene stack of  claim 1 , wherein the converted portion of the dielectric layer is formed in an oxidizing environment after patterning of the interconnect structure. 
   
   
     7. The damascene stack of  claim 6 , wherein the converted portion of the dielectric layer is formed after patterning of the interconnect structure using one of (i) a UV-ozone treatment and (ii) a SCCO2 treatment, the SCCO2 treatment including an oxidizer. 
   
   
     8. The damascene stack of  claim 1 , wherein the converted portion is removed using one of vapor HF and liquid HF. 
   
   
     9. The damascene stack of  claim 8 , wherein the converted portion is removed using a liquid HF solution having less than 5% HF. 
   
   
     10. The damascene stack of  claim 1 , wherein the damascene stack comprises a single damascene structure. 
   
   
     11. The damascene stack of  claim 1 , wherein the damascene stack comprises a dual-damascene structure. 
   
   
     12. The damascene stack of  claim 1  wherein the interconnect structure is formed from a conductive material. 
   
   
     13. The damascene stack of  claim 12 , wherein the interconnect structure comprises a diffusion barrier layer. 
   
   
     14. The damascene stack of  claim 1 , wherein the interconnect structure includes a conductive line formed in a horizontal trench. 
   
   
     15. The damascene stack of  claim 1 , wherein the interconnect structure includes a via. 
   
   
     16. The damascene stack of  claim 1 , wherein the converted portion of the dielectric layer is formed prior to formation of the interconnect structure. 
   
   
     17. The damascene stack of  claim 1 , wherein removing the converted portion occurs after formation of the interconnect structure. 
   
   
     18. The damascene stack of  claim 1 , wherein the dielectric material includes SiCO(H) and the dielectric material is locally converted to a material including SiO x  to form the converted portion. 
   
   
     19. The damascene stack of  claim 1 , wherein the converted portion has in plane dimensions smaller than 1 μm. 
   
   
     20. A damascene stack for use in a semiconductor device, the damascene stack comprising:
 a patterned dielectric layer including two interconnect structures, wherein the dielectric layer is formed of a dielectric material including Si, C and O; 
 a converted portion of the dielectric layer, wherein the converted portion extends substantially entirely between the two interconnect structures and has a lower carbon content than the dielectric material; and 
 at least one airgap formed between the two interconnects structures, the airgap being formed by removing substantially all of the converted portion using an etch compound.